Ecology of peatland testate amoebae in the Alaskan continuous permafrost zone

Abstract

This is a repository copy of Ecology of peatland testate amoebae in the Alaskan continuous permafrost zone.

Evidence for ecosystem state shifts in Alaskan continuous permafrost peatlands in response to recent warming

“…65.2%) in both fossil records, with a trend of increasing abundance with depth. This contrasts with the contemporary counts of this species, which are limited (Taylor et al, 2019). Similar records of C.…”

“…Testate amoebae were identified with the assistance of published guides (Charman et al, 2000;Booth and Sullivan, 2007;Siemensma, 2018). For the first time, we apply two modified transfer functions from continuous permafrost peatlands across the Alaskan North Slope (Taylor et al, 2019) to reconstruct WTD and EC.…”

“…Peat accumulation rate is slow (as expected in permafrost environments) throughout both cores, rapidly accelerating from the start of the industrial revolution (which we define as 1850 CE). To reconstruct EC, we used a Weighted Averaging model with inverse deshrinking (WA_inv), which is a different statistical approach than the WAPLS model used by Taylor et al (2019). This is because we found that the application of the WAPLS model led to erroneous results regarding C. pontigulasiformis, which suggested that this species was indicative of oligotrophic conditions owing to its rarity in the contemporary record and the model under fitting these data.…”

“…Testate amoeba-based reconstructions have been used in permafrost regions of Canada (Lamarre et al, 2012), Sweden (Swindles et al, 2015a), Finland and Siberia (Zhang et al, 2018), but their use has been limited to discontinuous and sporadic permafrost. We recently developed two new transfer functions from continuous permafrost peatlands across the Alaskan North Slope, which facilitate reconstruction of both WTD and porewater electrical conductivity (EC) during the Holocene, where EC can be used as a proxy for a peatland's trophic status along the fen-bog gradient (Taylor et al, 2019). By reconstructing Holocene hydrological change and calculating the carbon accumulation rate (CAR), we can begin to identify the environmental controls on these important variables in continuous permafrost peatlands.…”

“…Testate amoeba-based reconstructionsWe use the Weighted Averaging Partial Least Squares (WAPLS) second component model presented byTaylor et al (2019) to reconstruct WTD in both cores.Reconstructions with errors are shown alongside testate amoebae assemblages inFigures 3 and 4. TFS1 began with a high water table (Figure 5), but a rise in Centropyxis aerophila during the Little Ice Age (LIA) indicates a rapid transition to a deeper WTD.…”